Docker Swarm程式碼分析筆記（11）——Engine.Connect

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

Engine.Connect()方法用來完成對Docker engine的串連工作：

// Connect will initialize a connection to the Docker daemon running on the// host, gather machine specs (memory, cpu, ...) and monitor state changes.func (e *Engine) Connect(config *tls.Config) error {    host, _, err := net.SplitHostPort(e.Addr)    if err != nil {        return err    }    addr, err := net.ResolveIPAddr("ip4", host)    if err != nil {        return err    }    e.IP = addr.IP.String()    c, err := dockerclient.NewDockerClientTimeout("tcp://"+e.Addr, config, time.Duration(requestTimeout), setTCPUserTimeout)    if err != nil {        return err    }    // Use HTTP Client used by dockerclient to create engine-api client    apiClient, err := engineapi.NewClient("tcp://"+e.Addr, "", c.HTTPClient, nil)    if err != nil {        return err    }    return e.ConnectWithClient(c, apiClient)}

Engine.Connect()利用了另外兩個Docker項目：dockerclient和engine-api。首先調用dockerclient.NewDockerClientTimeout("tcp://"+e.Addr, config, time.Duration(requestTimeout), setTCPUserTimeout)產生一個DockerClient結構體：

type DockerClient struct {    URL           *url.URL    HTTPClient    *http.Client    TLSConfig     *tls.Config    monitorStats  int32    eventStopChan chan (struct{})}

再把DockerClient.HTTPClient傳入engineapi.NewClient()函數，作為engine-api的http.Client，作為HTTP請求的傳輸載體。最後調用Engine.ConnectWithClient()串連Docker engine，獲得Docker資訊。